This invention relates to improvements in a head supporting mechanism for a floppy disk apparatus.
A mechanism for supporting heads for reading data from a disk-like magnetic recording medium and writing data on the recording medium is known.
Such a head supporting mechanism disclosed, for example, in FIGS. 10 and 11 of U.S. Pat. No. 4,089,029 (Castrodale et al) is known. FIGS. 10 and 12 of Castrodale et al. show a head supporting mechanism comprising an arm, slender gimbal springs fixed at one end to the arm, heads fixed to the springs, and a spring pivot for urging the portions of the springs where the heads are mounted from the back sides toward the medium. The head supporting mechanism of this structure has various disadvantages as pointed out, for example, in the first and second columns of U.S. Pat. No. 4,151,573 (Tandon et al). More specifically, since the, gimbal springs have long and flexible leaf springs each fixed only at one end thereof on the corresponding arm, (1) The heads easily vibrate by deviation of the medium from its nominal plane, so it is difficult to obtaining good touch between the head and the recording medium. (2) The heads are weak to external vibrations. (3) The corners of the heads rub the surface of the recording medium when positioning the heads on the recording medium, the recording medium is readily damaged. (4) The manufacture is difficult.
Magnetic head supporting mechanisms disclosed in the Tandon et al patent and U.S. Pat. No. 4,306,258 (Higashiyama et al.) have been proposed to improve such disadvantages.
Tandon et al discloses a head supporting mechanism comprising a carriage, a head fixed to the carriage, an arm, a gimbal spring fixed to the arm, a head fixed to the spring, and a stationary pivot supporting the back surface of the gimbal spring at the distal end thereof. In Tandon et al, the head of the carriage side is fixed directly to the carriage, while the head of the arm, side is fixed to the gimbal spring. Since the back side of the gimbal spring is supported by the pivot, the gimbal spring does not substantially move in a direction normal to the nominal plane of the medium except that the head moves together with the arm. Thus, the heads can hardly follow to the movement of the recording medium is ironed out by forcing the gimbaled head toward the fixed head (1) Therefore, the life of the recording medium is shortened. (2) Further, the contacting characteristic of the recording medium with the heads is deteriorated. (3) Since the arm where the gimbaled head is mounted is heavy, and imposes a large mass of the arm on the gimbaled head, the head is weak for external vibration.
The Higashiyama et al discloses a head supporting mechanism comprising a carriage, arms fixed to the carriage, arms fixed to the bases, gimbal springs fixed to the arms, and heads fixed to the gimbal springs. The heads are loaded toward the medium only by the force produced by the deflection of the gimbal springs in this structure, the gimbal springs are sometimes mechanically overloaded and the life of the gimbal springs are shortened. Further, the durability of the gimbal springs is low. (2) Spring constants of the gimbal springs in the direction perpendicular to the recording medium cannot be set independently of spring constants of the gimbal springs both in the radial direction of the recording medium and in the direction tangential to the recording medium. Therefore, optimum spring constants cannot be obtained.